HS4 carb question

[sultanoswing]

I've got my SU's on the kitchen table for a rebuild, with 2 rebuild kits coming on Monday.

A question: what's the order/arrangement of how the flexible jet hose (connecting the float chambers to the jet) screws into the float chamber? I've pulled mine apart, so can't tell any more (doh!). Basically, there's the sleeve nut, the hose, the rubber washer, a steel washer and the 'gland'.

Thanks!

ps I've got the 'Tuning SU Carbs' book for reference too.

 

[John Moore]

that sounds about right. just make sure you dig out any old gaskets in from the threads in the float bowl. The old donuts tend to get stuck in there. One word of advice, do one carb at a time, so you have one to compare. Good luck! It's not too bad and very rewarding.

 

[sultanoswing]

Thanks...any idea of how to get the gland in - I don't want to damage it! Just a matter of putting in the float chamber exit point, aligning it, and screwing in the sleeve nut with the hose and washers in place?

I mean, I COULD wait until Monday to have a play with it, but I'm keen to learn as much as poss. before tackling it!

 

[DrEntropy]

IIRC the "sleeve" is a ferrule that should be placed inside the tube. If the kit is complete, I think new jets are part of it. The ferrule and gland nut will be already in place. Just pay attention to John's comment regarding the old washers in the bowl... I've seen many a car limping into the shop, gas dribbling out of the fitting due to a "double washer" error. The little SU toolkit in a plastic pouch comes in handy for centering the jets as well. Most times if you follow the outline in the manuals, you can bolt 'em on and balance 'em in fifteen minutes. Won't have to touch 'em again for a long time. Su's are just about "bullet proof".

 

[DrEntropy]

Just occurred to me: Linkage. I've seen sooo many cars come in with the complaint: "My mechanic pal rebuilt th' carbs, and now the thing won't get out of its' own way... can you look at it?"

Most of these problems were due to not being attentive on disassembly. The linkage for the butterflies can be fitted upside-down and usually is in these cases. Throttle cable can only pull it half way open then, car runs as if it had the anchor out.

Just an afterthought. HTH.

 

[sultanoswing]

Thanks for you replies - I'm just off to pick the kits up now...looking forward to a fun evening! (I see Jbird is doing the same thing on a nearby forum post!).

Now I really hope I don't start getting interested in CO2/O2 analysers and specialist needle selection /ubbthreads/images/graemlins/wink.gif

SoS

 

[DrEntropy]

On a slippery slope, you are. There's a nifty gas analyzer available for less than $500, you can set up a gas/air ratio needle profile CUSTOM made for your engine! Chuck the needles up inna drill and start applyin' 400 grit wet-or-dry at the proper places on each.... trial and error oughta get you inna ballpark in about, oh... ten years or so ;-}

 

[sultanoswing]

Damnnation, those carb refurb kits are expensive! $30USD for a couple of gaskets, a jet, rubber washers and (the bit I actually needed) a plastic sleeve/grommet for the float chamber connection - not even the OE brass nut! ...AND the POS plastic nut cross-threaded on me. I swear (and I'll swear alright) if it leaks through this POS thread tomorrow...

Anyway it's all done i I just gotta put 'em back on the car tomorrow morning (and hope she starts, without leaking fuel!) and balance 'em up. Very satisfying job, now I've got lovely shiny, clean carbs with new jets and fuel lines.

SoS

 

[DrEntropy]

If you leveled and centred the jets 'n needles then did the "thirteen flats" exercise it can't help but start!

 

[sultanoswing]

By thirteen flats, I'm assuming this is the equivalent of "two full turns" /ubbthreads/images/graemlins/smile.gif

Yep - all levelled and centered. Interestingly, one of the jets actually needed to be centred even though I didn't touch the locking nut, it was satisfying to get that done, I tell you! A gasket was missing from one of the float chambers, and the needles themselves weren't quite flush with the piston base. There was also a bit of carbon build up in the throttle bodies and lots of gunge on the linkages and throttle spindles...so all in all, they needed a refit, and they should be almost as good as new again! I'm actually so keen to get them fitted I'm going to get up real early tomorrow (it's Winter here) to get started.

I noted that the intakes and outflows have some very minor scratches on 'em....this starts getting me excited about proper gas flowing and sand blasting and ram pipes...where will it end?!

 

[Nunyas]

nope... "two full turns" is only 12 flats... you'll need one more "flat" side of the adjuster to make it a full 13 ... /ubbthreads/images/graemlins/smile.gif

 

[sultanoswing]

Well, she started...but is idling at about 2000, with the idle adjustment screws backed all the way off!

Is this an air leak somewhere? The butterfly vlaves appear to be closed from what I can see. The idle speed increases appreciably when I plug the dizzy vacuum advance in. I didn't use any gasket seal on the manifold, spacer and heat shield gaskets - should I have to avoid the chance of leaks?

 

[Nunyas]

did you check to make sure the throttle cable and/or linkage is not too tight? The last time I removed my carb I inadvertantly put the throttle cable back on too tight and it would not idle under 2K either.

After the throttle cable and linkages, I'd definitely go on a search for a leak in the system between the carb and head.

 

[sultanoswing]

Thanks - yes, the throttle & choke cables are actually removed, as I thought they could be the problem. I'll regasket everything this afternoon (with sealant) & check the closure of the butterflies with a flashlight from behind while I'm at it (possible soldering the little spring run-on valve everyone talks about which is known to fail).

 

[Nunyas]

is the vacuum advance line plugged while you have it disconnected from the distributor?

Oh yeah, I forgot earlier... I had a problem with my butterfly when I rebuilt my ZS, but that was because I had the butterfly shaft was put in backwards. It would never close all the way. I managed to catch that before reinstalling the carb though, because while visually checking the mechanical operation of the valves and linkages I found that it felt like it was binding near the closed position.

 

[sultanoswing]

Yep - it was the butterfly valves....those suckers have to be installed exactly the right way up and in exactly the right spot! After a couple of retries, I finally got both butterflies seated properly, and it was sweet music to my ears when she stalled with the throttles closed. Yet another thing learned!

I then made up a couple of new gaskets and sealed 'em all with sealant for good measure.

All tuned and balanced...now it's time to take her for a spin!!!

 

[DrEntropy]

WOOHOO!!!

Apologies for missing most of the last posts, but: Have you access to a Permatex product known as "Hylomar"? Best stuff for the intake gaskets. RTV tends to soften with exposure to petrol.

FUN, innit?!?

 

[sultanoswing]

Runnin' like a dream. It's good that after pulling so many bits off, the car does indeed run better than before I started. Throttle is smoother and no more pinking. Sweet (and FUN).

 

[DrEntropy]

SoS,
If I may be so bold as to ask: you onna north or south island?

 

[sultanoswing]

North Island, in Auckland - but soon to be moving to Hamilton.

SoS